Tracer for projectiles.



J. B. SEMPLE.

Patented De. 12,1911.

-Nrrn sbrarns AEN- FFICE.

JOHN B. SEMPLE, OF SEVVICKLEY, PENNSYLVANIA.

TRACER FOR PROJECTILES.

Specification of Letters Patent.

Patented Dec. 12, 1911.

Application filed April 24, 1911. `Serial No'. 622,960.

Y glieny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and usefull Improvements in Tracei's for Projectiles, of which improvements the following is a specification.

In Letters Patent of the United States,

' No. 581,946, granted to me May 4th, 1897,

f agent, bound in a coherent mass with such CII projectiles.

-jectile flies.

I have shown and described a tracer for The tracer consists of a body of slow-burning, light-giving substance, carried in an open-mouthed chamber or cell in the body ofthe projectile, ignited on the firing of the projectile from aA gun, and burning from. the open mouth of the cell as the pro- In the said. patent I have shown and described the tracer cell as opening preferably to the rear-that is, with its mouth exposed to the flash ofthe propelling charge. For a tracer conipositioinI have specified (by way of example) a mixture of magnesium. gunpowder, and an oxidizing binder as shellac. Such a tracer material I have described as capable of being ignited, either directly by the flash of the propelling charge, or indirectly through mechanical means.

Although I have, since the grant of the aforesaid patent, extensively practiced the invention which is described in it, I have heretofore found it impracticable, when dealing with projectiles fired at modern high -pressures, to ignite (withoutexplodin l byghnz flash of the propelling charge. I have found, in guns iired at modern high pressures, that, if the charge of tracer material 4be exposed to the Hash of firing, it

lwill either be utterly consumed on the instant. or so far destroyed that the tracer `cannot be made to burn through a sufficient. portion of the trajectory of the projectile to render the tracer certainly useful to any substantial or vadequate degree. Ac.- cordingly, up to the present time, VI have been obliged,v in making tracers for use in guns fired at such high pressures as have of late years been commonly employed, to .re-

sort to indirect means for effecting ignition l of the tracer on the tiring ofthe projectile which carries it. Such necessity 1s disad-A f'antageous, in that simplicity of structure he charge of tracer material directlyv `here refer, is to add apprcciably to the cost of the tracer-equipped projectile.

A compound of materials suitable for the tracer charge has been referred to above;

and, while my present invention is not lim ited to the use of any particular composition, I shall for purposes of explanation continue to refer to this particular composition. This composition is a mixture of magnesium, gunpowder, and an oxidizing agent, held together by a suitable binder, such as shellac. The preparation of the, composition, as it has heretofore been carried out, has consisted in compounding the ingredients essential for burning with the binder and subjecting the whole to a suflicient amount of pressure to cause the mass to cohere and keep its place in the chamber or cell prepared for it in the body of the projectile.

.of the ingredients essential for burning and the binder be compressed to a degree far exceeding that required to effect cohesion of the mass, and to a pressure measurably approaching (or even equaling or exceeding) the gaseous pressure produced on the explosion of the propelling charge under which the projectile is to be tired, the .charge of tracer material may b e exposed fory ignition to the iiash of the propelling charge, and will not on the firing of the gun be prematurely consumed or destroyed to an injurious degree', even though fired under such high pressure as I have particularly referred to above; and (contrary to what might have been expected) will not under such circumstances resist initial ignition or progressive burning as the projectile flies, but will perform its function in proper and desired manner. l

4 I have found that tracer material so coinpounded and compressed owes its practical success under the exacting conditions of modern high-pressure service to the substan- I prepared according-to my present invention is dense, and does .not permit such destructive j'ai-netI-ation, and is not prematurely dest royed .'\ccordingly, my invention, in its broadest aspect, consists in compressing the tracer compound to a. degree so greatI as t o substantially exclude `gas penetration under the exacting; conditions abovereferred to; and, while I have indicated that compression to a degree approximating the pressure generated in the gun on the explosion of the propelling' charge will be effective to the end in view, I donot. desire to measure the degree of pressure by that ligure.

My invention will be embodied, if the materia'l be compressed to a higher degree than has heretofore been supposed necessary or desirable, 'with the attendant result that the compressed material is resistant to r(rases which otherwise would permeate and prematurely destroy` it.

It, will thus be seen that. if it be known beforehand (within reasfmable limits) what the degree of pressure will be to which a certain projectile is to be subjected when `tired, the manufacturer of the tracer may govern accordingly the degree of compression to which the tracer material is in its preparation subjected, and in so doing' adapt his product to the particular' service conten'iplated. IVhilc the gas pressure Agenerated on the discharge, of a projectile may not be determined in advance with absolute accuracy, it. mayA within workable limits be predetermined.

The invention resides both in the method of production and in the product obtained.

I have spoken above of shellac as a suitable binding material for use in the practice of my invention, and have said that it. is requisite that the binding material be plastic at the temperature under which the tracer material is compressed. lVhile I preferably add lto the component-s necessary for combustion another ingredient. such as shellac, rosin, orlinseed oil, which (While having' no substantial effect upon the proper function of the tracer ingredients with. which it iscompounded) will serve its own function of holding these ingredients in a coherentmass, the ingredients of the tracer composition itself may include an element or elements efecting underpressure the desired cohesion. ment of gnnpowder, forexamplel (when gunpowder is employed in the tracer com position), becomes plastic at moderately elevated temperature; and, by compressing gunpowder With other ingredients at such temperature, the sulfur element in the gun-v powder may if desired be relied on to 'serve as the binder.

In the accompanying' drawings which form part of this specification, Figure 1 is The sulfur eleclosing the mouth of the chamber.

a view in longitudinal section of a projectile equipped with a tracer, and illustrates my invention in the general aspect hereinabove described. In this drawing, the projectile body is indicated at 1and the tracer stock` (for the tracer cell is preferably formed in a separate piece or member) is indicated at 2, and the tracer material within the` cell is indicated at 3. This material 3 is the material which is comj'n'essed in the manner and to the degree above indicated, and it will be observed that the mouth S of the cell open rearwardly of the projectile, and is accordingly in a position to be directly exposed to the flash of thepropellingcharge, when the projectile is tired from a gun.

Figs. 3. 4. and 5 are views in longi-` tudinal section of the tracer stock det-ached from the projectile. and illustrate (in alternative form) a temporary protective closure tor the otherwise open mouth of the tracer cell; Figs. -Iv and 5 serve also to illustrate lhe application to the main body of tracer material. and at the rear thereof, of a supplementary, readily ienitible body of material which serves to insure the ignitibir of the highly compressed tracer body. I shall describe firstv this supplel'nental ignition body. 4

`Vhile I have found the body of tracer material to be ignitible by the [lash of the charge, even though highly conipressed to resist penetration by the gases generated in high-pressure work, I have reason to think that in the range of permissible and de.-=iral'ile materials, and inl the rang-e of pressure which practicallconditions may require. diiliculty may at times arise, through 'failure of ignition. I have found it faisible and practical to insure ignition under otherwise unfavorable conditions by forming with or applying to the main body 3 of tracer material a supplementary body of'material (8b of Figf, 3 of Fig 5) rendered more readily ignitible either by smaller degree of compression, or

'by beingT compounded of more iniammable material (such as black powder, magnesium, and niter, compounded in different proportions than those suited for tracer material, having a relatively larger black powder content), or both, andarrangedl at the rear of the`main tracerbody, and in a position directly exposed to the flash of discharge.

The-means shown in. Fig.- 2 fo'r protecting thel body of tracer material Within its cellfrom injury consi-st of a disk 4, temporariy s Shown in the ligure, this disk is preferably of somewhat greater diameter than the bore of the cell, is countersunk in the mouth of the cell, and may conveniently be secured in place With adequate firmness by crimping" the lip of the orifice over the rear edge of losv Q, 3, anu T, 'the tracer' chamber, `ind between the rear the disk, asis indicated at 5. This disk t is perforate, and the hole through it is closed by a plug 6, of material destructible or removable by the flash or pressure of the propelling charge lead, for example, or other relatively soft material, such as wax. The flash of discharge will penetrate through the plugged perforation in disk et and gain access to the body of tracer ma.- terial to ignite it. `Wlien the discharged projectile leaves the gun, the disk 4 will be removed from its temporary security in the mouth of the cell by the pressure of gas in front of it, and thereafter the tracer will burn from the open mouth.

lThe alternative form of closure illustrated in Fig. 3 contemplates protection of the means employed from injurious eilects of the air. If the plate 4 be used as it is shown in Fig. il, it will preferably be formed of non-corrosive metal, such as brass. The sea air, to which such articles are very coinmonly exposed, will corrode and injure this part of the structure, if'it be in any substantial degree corrosiye. Noncorrosive materials are however relatively expensive, and in Fig. 3 I have shown that a disk 4ta made of cheaper but corrosive material, may

be protected from the air by a` cover-plate 7 ofI non-corrosive.material such, for example, as brass. If such a cover-plate be employed, it Will be of relatively light Weight, readily penetrable (where unsupportedlby the i'lash of discharge. The perforation in the plate 4 will not Abe plugged, and the flash of discharge will pierce the cover plate 7 and gain access through the perforation to the body of tracer material.

in Fig. 4, the disk ib (preferably of brass), instead ofbeing relatively heavy and perforate, is relatively light and iur perforate, and the flash of discharge gains access to the tracer by piercing the imperforate disk.

In Fig. the protecting disk becomes a membrane 4C, ofvsuch thin material as tin foil or sliellacked paper, which the flash of discharge Will even more readily pierce. It will be observed that in Fig. 5 the closure is not countersunk in the mouth of the tracer cell (as in Figs. 2, 3, and 4;) but the closure, being of flexible material,v is shaped to conform to and be secured to the unenlarged bore of the cell.

`l t will be observed, on reference to Figs. than an air space is left Within face of the compressed tracer compound and the forward face ,of the temporary protecting disk. I have found the presence of such a space desirable; for, when present, 'the action of the flash of discharge in penetrating the temporary protecting covering and getting access to the tracer compound itself is facilitated. If, for certainty of ignition or otherwise, the body of tracer material (otherwise impervious), be, at its posterior end, of diminished density, and so penctrable by the gases of discharge, the air space between closure and tracer body may Without detriment be eliminated. This feature is indicated in Fig. 5, wherein the supplemental body 3c (whether of uniform composition with the main body 3 or of a composition more readily ignitible) will be understood to be less dense than the main body 3, and previous to high-pressure gases. The closure 4" may then, as the ligure shows, bear directlyupon the posterior face 'of the tracer charge.

A further structural detail will readily be understood, Without further illustration. If the closure be formed of inflammable inaterial, such as collodion. the closure may be laid directly against the posterior face of the tracer charge, even though the tracer charge be highly compressed throughout. lf such a material as collodion be used as a closure, itvvill preferably be protected externally by a coating of easily fusible Weather-proof material, such as Wax, or'

sliellac varnish.

I claim herein as my invention: l. The herein described method of preparing a body ot tracer material for service in projectiles tired at high pressure, which consists in compounding and compressingy the tracer ingredients to a degree of pressure in excess of that required to afford cohesion and to a degree rendering such body resistant to immediate destruction when the projectile furnished with it is iired at its intended service pressure.

2. The herein described method of preparing a body of tracer material for service in projectiles fired at high pressure, which consists in compounding the tracer ingredients, and compressing such compound to a degree of pressure in excess of that required to afford cohesion, and sufficient to render the nass impervious to gas penetration when exposed to the high pressure incident to its intended service.

3. -The method herein described of preparing a tracer charge for a projectile tired under predetermined conditions of gas pressure, which consists in compressing one portion of the body of the charge to the degree in excess of that required to give cohesion and arranging contiguous to such highly compressed portion another portion less highly compressed.

4. A body of tracer material adapted for service Within a projectile tired under con ditions of high pressure, such body of tracer material compounded and compressed to a degree in excess of the pressure required to give cohesion, and to the point of resistance 5. A tracer charge for a projectile fired under predetermined conditions of gas pressure, one portion of the said charge compressed to the exclusion of gas` penetration under the conditions ot discharge and anotlierand contiguous portion of said charge penetrable by the gases of discharge, substantially as described.

G. A tracer charge for a projectile fired under predetermined conditions of gas pressure, one portion of the said charge composed of tracer material and compressed to the exclusion o'f gas penetration under the conditions of discharge, and another and contiguous portion of said charge composed or more readily ignitible material, substantially as described.

7. A projectile having a cell open at its rear end, in combination 'with a combustible non-explosive or pyrotechnic compound arranged in said cell and compressed to a degree in excess of that necessary to afford cohesion and to the exclusion of tration, substantially as described.

8. The combination of a projectileka rear- Wardly opening tracer cell formed therein, a body of tracer material Within lsaid cell compressed to the exclusion of gas penetragas penetion under the conditions of discharge,.

and a closure for said tracer cell penetrable hy thevflash of the propelling charge, substantially as described.

9. The combination of a projectile, a rearwardly opening tracer cell formed therein,

a body of tracer material Within said cell the flash of the "propelling charge, and re-l movable by the combustion of the tracer material Within its cell as the projectile flies, substantially as described.

10. The combination of a projectile, a tracer cell formed therein and opening rearwardly, a-body of tracer material Within said cell, impervious by compression to penetration by the gases of explosion, a closure for said cell rearward, said closure being penetrable by the flash. of the propelling charge, and said closure being spaced at an interval from the body of tracer material Within the cell, substantially as described.

11. The combination of a projectile provided With a rearwardly opening tracer cell, a body of tracer material Within said cell and compressed to the prevention of penetration of gases of explosion, a perforate plate closing the said tracer cell, and a closure for the perforation in said plate, said closure removable by the flash of the propelling charge, substantially as described.

In testimony whereof I have hereunto set my hand.

JOHN B. SEMPLE.

Witnesses;

ALICE A. TRILL, PAUL N. CRITCHLOW. 

